Switch keys and other manually actuated components for enabling operator interaction with an electrical circuit are usually provided with a label or symbol that identifies the function of the key or the like. It is advantageous if the label or symbol appears on the key cap itself as this avoids errors in associating a particular label with a particular key. The labels are necessarily located on the key caps in instances where a plurality of keys are arrayed in adjacent relationship with each other such as in a computer keyboard for example.
Traditional practice has been to provide permanent imprinted labels on key caps. This complicates operation of switch keys in instances where the same switch is used for different purposes at different times. A computer keyboard is again an example of an electronic device in which problems of this kind arise. Individual function keys on the computer keyboard are used to enter different instructions to the computer during different modes of operation of the system. Alphanumeric keys, which are used to enter letters or numbers, may have alternate functions when operated in conjunction with other keys. The function of a particular key may depend on the particular software that is being run.
The operator of a keyboard in which keys are permanently imprinted with a single label or a small number of labels must typically memorize alternate functions of different keys or repeatedly consult a list of such functions. This complicates the process of learning to operate the keyboard, slows operation and tends to promote operator error.
It is possible to provide a template which extends alongside certain keys and which is imprinted with words or symbols that identify alternate functions of the keys. This is not an ideal solution to the problem as the words or symbols are not situated directly on the keys and the operator's attention must be momentarily diverted from the actual keys to inspect the template. A template of this kind can only be used in conjunction with keys which are separated from the main bank of keys or which are at certain locations at the periphery of the bank of keys.
It has heretofore been recognized that operation of keys or switch buttons which have multiple functions can be facilitated by embedding small flat panel displays in the key caps which displays are of the type that electronically generate changeable images. The labels or symbols displayed by the key can then be made to change when the function of the key changes.
The traditional flat panel display construction is not ideally suited for this purpose. The active image generating area of such displays is bounded by a sizable bezel region which contains moisture seals, electrical conductors and other components. Thus the image display area is smaller than the overall area of the display panel. This severely constricts the size of the displayed images in instances where the display panel is very small as is the case where it is to be embedded in a switch key cap. The face of a key may, for example, measure one half inch by one half inch. The bezel region at each edge of prior flat panel displays is at least one eighth inch to one fourth inch wide. Such a bezel would leave little or no usable viewing area on a one half inch square display. The display would have an undesirably limited information content or none at all.
One prior flat panel display technology provides image display areas that extend to the edges of the panels. For several reasons, prior displays of this kind are not particularly suited for use in small switch caps. For example, the seals at the edges of a flat panel display of this kind should be extremely thin as seals having a thickness in excess of about ten mils create a noticeable bezel around the margins of the image display area. In the absence of the present invention, seals this thin may deteriorate over a period of time and allow a damaging infiltration of moisture. This shortens the usable life of the key and can cause line outs in the image.
Components of prior flat panel displays which produce images that are coextensive with the face of the panel are not arranged and interrelated in a manner that is susceptible to miniaturization of the device for inclusion in a small switch key, at least in instances where high resolution images are to be produced. Use in a switch key cap requires that integrated circuit chips and a large number of minute conductors for interconnecting the chips with pixel defining busbars of the display all fit within the confined region behind the face of the switch cap and that they be arranged in a manner which enables the numerous electrical interconnections to be established in a reliable manner.
Considering another aspect of the background of the invention, the use of diverse different electronic devices in homes, offices, vehicles and at other locations creates certain complications for the users which have not heretofore been addressed. Each such device has its own set of controls which the user must learn to operate. Duplication of controls adds substantially to the cost and bulk of the electronic devices. In some situations it may be difficult or impossible to find convenient locations for a sizable number of sets of controls for different electronic devices. Automobiles, for example, may be equipped with a radio, a cassette player, a compact disc player and/or any of a variety of other electronic systems. The dashboard of a typical car provides little or no space for a proliferation of additional controls. In a home, electronic devices may be situated at widely spaced apart locations. The user must move from one place to another in order to operate the different devices or, alternately, operate a number of different hand held remote control units.
The present invention is directed to overcoming one or more of the problems discussed above.